System set up in front of corner Vs flat wall - acoustical issues?

The advantage of a corner placement for speakers is the corner and floor reinforce the bass, so you actually have more output in SPL terms.  You can get too much, your ears will tell you this.  If you have tall subwoofers, you get the effect the ceiling as well, so the bass SPL really goes up.  Think of it as a horn subwoofer and you get the idea. 

The same effect applies to the main speakers as well, but to a lesser degree due to the frequencies involved.   But do try it, you might prefer it over other arrangements. 

In my room, the right subwoofers are in a corner and the left channel subwoofers are on a flat wall.  I am going to redo the room so that both subwoofers are in the corner.  It also gives me more seating area in the far field of the speakers and less in the near field, which should be a good thing.

Corner layouts usually work pretty good, even better if you move the speakers forward and the TV back. 

Lots of systems u see speakers maybe 2 feet from the walls and then some room u see them coming out 8 feet from the walls.
I guess there’s a lot to be said byreally pulling out the speakers if your room can handle it

Am I misunderstanding your question?

It almost reads to me as if you are wondering about using one of the corners of your room as the back drop for the speakers versus one of the flat walls being the back plane for your speakers?

The backdrop of the system is the corner. Behind the rack and the two main speakers on each side is the corner of the room.  Angling out the system to the rest of the room from the corner may be a few degrees toward the center of the room but pretty much it's going to be based from the corner.